Variable displacement compressor

ABSTRACT

An object is to provide a variable displacement compressor in which a structure is simple and it is easy to lay out valves. On a downstream side of a first control valve that controls an opening degree of a pressure supply passage, a second control valve is provided, which includes a spool having a first valve portion and a second valve portion. When a pressure Pm of the pressure supply passage is higher than a pressure Pc of the crank chamber, the first valve portion opens the pressure supply passage, and the second valve portion closes the first pressure release passage. When the pressure Pm is lower than the pressure Pc, the first valve portion closes the pressure supply passage, and the second valve portion sets an opening degree of the first pressure release passage to a maximum opening degree.

TECHNICAL FIELD

The present invention relates to a variable displacement compressor, and specifically, relates to a variable displacement compressor in which a discharge displacement is controlled by pressure regulation in a crank chamber.

BACKGROUND ART

Patent Documents 1 and 2 each disclose a variable displacement compressor including: a supply passage for supplying a refrigerant in a discharge pressure area to a crank chamber; a bleed passage for discharging the refrigerant in the crank chamber to a suction pressure area; a first control valve that adjusts a passage cross-sectional area of the supply passage; a second control valve that closes the bleed passage when a downstream pressure of the first control valve becomes high; a check valve that is disposed in the supply passage between the first control valve and the crank chamber and blocks a flow of the refrigerant directed toward the first control valve from the crank chamber.

REFERENCE DOCUMENT LIST Patent Documents

Patent Document 1: Japanese Patent Application Laid-open Publication No. 2010-106677

Patent Document 2: Japanese Patent Application Laid-open Publication No. 2011-185138

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

Incidentally, in such a variable displacement compressor individually including: a first valve device that controls supply of a working fluid to the crank chamber; a second valve device that controls discharge of the working fluid from the crank chamber; and a third valve device that blocks a reverse flow of the working fluid directed toward the first valve device from the crank chamber, a structure of the variable displacement compressor becomes complicated, and moreover, it is difficult to lay out the second valve device and the third valve device in the compressor without increasing a size of the compressor.

In this connection, it is an object of the present invention to provide a variable displacement compressor in which a structure is simple and it is easy to lay out valves.

Means for Solving the Problems

In order to achieve the foregoing object, a variable displacement compressor according to the present invention is a variable displacement compressor in which a discharge displacement is controlled by pressure regulation in the crank chamber, including: a first control valve that controls an opening degree of a pressure supply passage that causes a discharge chamber and the crank chamber to communicate with each other; and a second control valve including a spool having a first valve portion that opens and closes the pressure supply passage between the first control valve and the crank chamber and a second valve portion that opens and closes a pressure release passage that causes the crank chamber and a suction chamber to communicate with each other,

wherein the spool moves in response to a difference between a pressure of the pressure supply passage between the first control valve and the second control valve and a pressure of the crank chamber,

when the pressure of the pressure supply passage between the first control valve and the second control valve is higher than the pressure of the crank chamber, the first valve portion opens the pressure supply passage to supply a fluid from the discharge chamber to the crank chamber, and the second valve portion sets an opening degree of the pressure release passage to a minimum opening degree, and

when the pressure of the pressure supply passage between the first control valve and the second control valve is lower than the pressure of the crank chamber, the first valve portion closes the pressure supply passage to block a reverse flow of the fluid directed from the crank chamber toward the first control valve, and the second valve portion sets the opening degree of the pressure release passage to a maximum opening degree.

Effects of the Invention

According to the variable displacement compressor of the present invention, the second control valve has such a function to control the discharge of the fluid from the crank chamber and such a function to block the reverse flow of the fluid from the crank chamber to the discharge chamber side, and the structure of the compressor becomes more simple and it becomes easier to lay out the valve devices in the compressor than in the case where the valve devices which exert the respective functions are individually provided.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a variable displacement compressor in a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of a first control valve in the first embodiment of the present invention.

FIG. 3 is a graph illustrating a correlation between a coil energization amount and a set pressure in the first embodiment of the present invention.

FIGS. 4A and 4B are cross-sectional views of a second control valve in the first embodiment of the present invention: FIG. 4A is a cross-sectional view illustrating a pressure supply state to a crank chamber; and FIG. 4B is a cross-sectional view illustrating a pressure release state from the crank chamber.

FIGS. 5A and 5B are cross-sectional views of a second control valve in a second embodiment of the present invention: FIG. 5A is a cross-sectional view illustrating a pressure supply state to a crank chamber; and FIG. 5B is a cross-sectional view illustrating a pressure release state from the crank chamber.

FIG. 6 is a cross-sectional view of a second control valve in a pressure supply state to a crank chamber in a third embodiment of the present invention.

FIG. 7 is a cross-sectional view of a second control valve in a pressure supply state to a crank chamber in a fourth embodiment of the present invention.

MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

First Embodiment

FIG. 1 to FIG. 4 illustrate a variable displacement-type clutchless compressor applied to a vehicle air conditioning system (an air conditioner system).

A variable displacement compressor 100 illustrated in FIG. 1 includes: a cylinder block 101 in which a plurality of cylinder bores 101 a are formed; a front housing 102 provided on one end of the cylinder block 101; and a cylinder head 104 provided on other end of the cylinder block 101 via a valve plate 103.

A crank chamber 140 is formed of the cylinder block 101 and the front housing 102, and a drive shaft 110 is provided across an inside of the crank chamber 140.

A swash plate 111 is disposed around an axially intermediate portion of the drive shaft 110.

The swash plate 111 is coupled to a rotor 112, which is fixed to the drive shaft 110, via a link mechanism 120, and is configured so that an inclination angle of the swash plate 111 along the drive shaft 110 can be changeable.

The link mechanism 120 includes: a first arm 112 a protruded from the rotor 112; a second arm 111 a protruded from the swash plate 111; and a link arm 121, in which one end is rotatably coupled to the first arm 112 a via a first coupling pin 122, and other end is rotatably coupled to the second arm 111 a via a second coupling pin 123.

A through hole 111 b of the swash plate 111 is formed into such a shape that the swash plate 111 is capable of tilting within a range between a maximum inclination angle and a minimum inclination angle, and in the through hole 111 b, a minimum inclination angle restricting portion (not illustrated) that abuts against the drive shaft 110 is formed.

When an inclination angle of the swash plate 111 when the swash plate 111 is perpendicular to the drive shaft 110 is 0 degrees, the minimum inclination angle restricting portion of the through hole 111 b is formed such that the swash plate 111 can be inclined and displaced up to approximately 0 degrees. Moreover, the maximum inclination angle of the swash plate 111 is regulated in such a manner that the swash plate 111 abuts against the rotor 112.

An inclination angle decreasing spring 114 that urges the swash plate 111 toward the minimum inclination angle is mounted between the rotor 112 and the swash plate 111, and an inclination angle increasing spring 115 that urges the swash plate 111 toward a direction of increasing the inclination angle thereof is mounted between the swash plate 111 and a spring support member 116 provided on the drive shaft 110.

Here, urging force of the inclination angle increasing spring 115 at the minimum inclination angle is set larger than urging force of the inclination angle decreasing spring 114, and when the drive shaft 110 does not rotate, the swash plate 111 is positioned at an inclination angle at which the urging force of the inclination angle decreasing spring 114 and the urging force of the inclination angle increasing spring 115 are balanced with each other.

One end of the drive shaft 110 penetrates an inside of a boss portion 102 a protruding to an outside of the front housing 102, extends to the outside of the front housing 102, and is coupled to a power transmission device (not illustrated).

A shaft sealing device 130 is inserted between the drive shaft 110 and the boss portion 102 a, and shields the crank chamber 140 and an external space from each other.

A coupled body of the drive shaft 110 and the rotor 112 is supported by bearings 131 and 132 in a radial direction, and is supported by a bearing 133 and a thrust plate 134 in a thrust direction.

Then, power from an external drive source is transmitted to a power transmission device, and the drive shaft 110 is rotatable in synchronization with rotation of the power transmission device.

Note that a clearance between the thrust plate 134 and a portion of the drive shaft 110 against which the thrust plate 134 abuts is adjusted to a predetermined clearance by an adjustment screw 135.

A piston 136 is disposed in the cylinder bore 101 a, an outer peripheral portion of the swash plate 111 is housed in an inner space of an end portion of the piston 136, which protrudes toward the crank chamber 140, and the swash plate 111 is configured to be linked with the piston 136 via a pair of shoes 137. Then, the piston 136 reciprocates in the cylinder bore 101 a by rotation of the swash plate 111.

In the cylinder head 104, a suction chamber 141 is formed in a center portion thereof, and in addition, a discharge chamber 142 that annularly surrounds a radially outer side of the suction chamber 141 is defined and formed.

The suction chamber 141 and the cylinder bore 101 a communicate with each other via a communication hole 103 a provided in the valve plate 103 and via a suction valve (not illustrated) formed in a suction valve forming plate 150. The discharge chamber 142 and the cylinder bore 101 a communicate with each other via a discharge valve (not illustrated) formed in a discharge valve forming plate 151 and via a communication hole 103 b provided in the valve plate 103.

The above-described front housing 102, a center gasket (not illustrated), the cylinder block 101, a cylinder gasket 152, the suction valve forming plate 150, the valve plate 103, the discharge valve forming plate 151, a head gasket 153 and the cylinder head 104 are sequentially connected to one another, and are fastened by a plurality of through bolts 105, whereby a compressor housing is formed.

Moreover, a muffler is provided in an upper portion of the cylinder block 101 in FIG. 1. The muffler is formed in such a manner that a lid member 106 that has a discharge port 106 a opened therein and a formed wall 101 b defined and formed on the upper portion of the cylinder block 101 are fastened to each other by the bolts via a sealing member (not illustrated).

A discharge check valve 200 is disposed in a muffler space 143 surrounded by the lid member 106 and the formed wall 101 b.

The discharge check valve 200 is disposed at a connecting portion between the muffler space 143 and the communication passage 144 that causes the discharge chamber 142 and the muffler space 143 to communicate with each other. The discharge check valve 200 operates in response to a pressure difference between the communication passage 144 (an upstream side) and the muffler space 143 (a downstream side), shuts off the communication passage 144 when the pressure difference is smaller than a predetermined value, and opens the communication passage 144 when the pressure difference is larger than the predetermined value.

Hence, the discharge chamber 142 is connected to a discharge-side refrigerant circuit of the air conditioning system via a discharge passage formed of the communication passage 144, the discharge check valve 200, the muffler space 143 and the discharge port 106 a.

In the cylinder head 104, a suction passage composed of a suction port (not illustrated) and a communication passage 104 a is linearly extended so as to cross a part of the discharge chamber 142 from a radially outside of the cylinder head 104. The suction chamber 141 is connected to a suction-side refrigerant circuit of the air conditioning system via this suction passage.

A pressure supply passage 145 that causes the discharge chamber 142 and the crank chamber 140 to communicate with each other is formed in the cylinder head 104, and a first control valve 300 that controls an opening area (an opening degree) of the pressure supply passage 145 is provided.

The first control valve 300 is housed in a housing hole 104 b formed along such a radial direction of the cylinder head 104. The first control valve 300 adjusts the opening degree of the pressure supply passage 145 in response to a pressure of the suction chamber 141, which is introduced via a communication passage 104 c, and in response to electromagnetic force generated by a current flowing through a solenoid according to an external signal, thereby controlling a discharge gas introduction amount (a pressure supply amount) to the crank chamber 140.

In the pressure supply passage 145 located downstream of the first control valve 300, a second control valve 350 is disposed.

As illustrated in FIGS. 4A and 4B, the second control valve 350 is composed by including a spool 352 having: a first valve portion 352 a that opens and closes the pressure supply passage 145 between the first control valve 300 and the crank chamber 140; and a second valve portion 352 b that opens and closes a pressure release passage 146 b that causes the crank chamber 140 and the suction chamber 141 to communicate with each other.

The spool 352 moves in response to a difference between a pressure of the pressure supply passage 145 between the first control valve 300 and the second control valve 350 and a pressure of the crank chamber 140. In this way, the second control valve 350 has a function as a check valve that blocks a reverse flow of the refrigerant (a fluid), which is directed from the crank chamber 140 toward the first control valve 300, and a function to control discharge of the refrigerant from the crank chamber 140 to the suction chamber 141.

Moreover, as the pressure release passage 146 that discharges the refrigerant in the crank chamber 140 to the suction chamber 141, a pressure release passage 146 b (a first pressure release passage), which passes via the second control valve 350 and is opened and closed by the second control valve 350, is provided. In addition, as the pressure release passage 146, a pressure release passage 146 a (a second pressure release passage), which passes via a communication passage 101 c, a space 101 d and a fixed throttle 103 c formed in the valve plate 103 and bypasses the second control valve 350, is provided.

Note that a flow passage cross-sectional area of the first pressure release passage 146 b when the first pressure release passage 146 b is opened by the second control valve 350 is set larger than a flow passage cross-sectional area of the fixed throttle 103 c of the second pressure release passage 146 a.

Then, when the first control valve 300 closes, and a pressure of the pressure supply passage 145 between the first control valve 300 and the second control valve 350 becomes lower than a pressure of the crank chamber 140, then the second control valve 350 closes the pressure supply passage 145 to block the reverse flow of the refrigerant directed from the crank chamber 140 to the first control valve 300, and meanwhile, sets an opening degree of the first pressure release passage 146 b to a maximum opening degree.

In this way, the refrigerant in the crank chamber 140 is rapidly discharged into the suction chamber 141 via the second pressure release passage 146 a and the first pressure release passage 146 b, and the pressure of the crank chamber 140 becomes equivalent to the pressure of the suction chamber 141 to bring the maximum inclination angle of the swash plate, whereby a piston stroke (a discharge displacement) becomes maximum

Moreover, when the first control valve 300 opens, and the pressure of the pressure supply passage 145 between the first control valve 300 and the second control valve 350 becomes higher than the pressure of the crank chamber 140, then the second control valve 350 opens the pressure supply passage 145 and closes the first pressure release passage 146 b.

In this way, the refrigerant in the discharge chamber 142 is supplied to the crank chamber 140 via the pressure supply passage 145, and meanwhile, the refrigerant in the crank chamber 140 is restricted from flowing into the suction chamber 141, and the pressure of the crank chamber 140 becomes likely to rise. Then, the pressure of the crank chamber 140 rises in response to the opening degree of the first control valve 300, and the inclination angle of the swash plate 111 decreases from the maximum, whereby the piston stroke can be variably controlled.

As described above, the variable displacement compressor 100 is a compressor in which a discharge displacement is controlled by the pressure regulation in the crank chamber 140.

Note that a structure and functions of the second control valve 350 will be described later in detail.

Oil for lubrication is sealed in an inside of the variable displacement compressor 100, and the inside of the variable displacement compressor 100 is lubricated by agitation of the oil, which accompanies the rotation of the drive shaft 110, and by movement of the oil, which accompanies the movement of the refrigerant gas.

First Control Valve

FIG. 2 is a longitudinal sectional view illustrating an example of the first control valve 300.

The first control valve 300 in FIG. 2 is composed of a valve unit and a drive unit (a solenoid) that opens and closes the valve unit.

The valve unit of the first control valve 300 includes a cylindrical valve housing 301, and in an inside of the valve housing 301, a first pressure sensing chamber 302, a valve chamber 303 and a second pressure sensing chamber 307 are formed in an axial direction in this order.

The first pressure sensing chamber 302 communicates with the crank chamber 140 via a communication hole 301 a formed on an outer circumferential surface of the valve housing 301, and via a housing hole 104 b and a communication passage 104 f, which are formed in the cylinder head 104.

The second pressure sensing chamber 307 communicates with the suction chamber 141 via a communication hole 301 e formed on the outer circumferential surface of the valve housing 301, and via the communication passage 104 c formed in the cylinder head 104.

The valve chamber 303 communicates with the discharge chamber 142 via a communication hole 301 b formed on the outer circumferential surface of the valve housing 301, and via a communication passage 104 k formed in the cylinder head 104.

The first pressure sensing chamber 302 and the valve chamber 303 are made communicable with each other via a valve hole 301 c.

A support hole 301 d is formed between the valve chamber 303 and the second pressure sensing chamber 307.

In the first pressure sensing chamber 302, a bellows 305 is disposed. The bellows 305 evacuates an inside thereof and incorporates a spring therein, is disposed so as to be displaceable in the axial direction of the valve housing 301, and has a function as pressure sensing means for receiving the pressure of the first pressure sensing chamber 302, that is, in the crank chamber 140.

In the valve chamber 303, a columnar valve body 304 is housed. The valve body 304 is slidable in the support hole 301 d while an outer circumferential surface thereof is in close contact with an inner circumferential surface of the support hole 301 d, and is movable in the axial direction of the valve housing 301. One end of the valve body 304 is capable of opening and closing the valve hole 301 c, and other end of the valve body 304 protrudes into the second pressure sensing chamber 307.

One end of a rod-like coupling portion 306 is fixed to one end of the valve body 304. Other end of the coupling portion 306 is disposed so as to be capable of abutting against the bellows 305, and has a function to transmit such displacement of the bellows 305 to the valve body 304.

The drive unit has a cylindrical solenoid housing 312, and the solenoid housing 312 is coupled to other end of the valve housing 301 coaxially therewith.

In the solenoid housing 312, a molded coil 314 in which an electromagnetic coil is covered with resin is housed.

Moreover, a cylindrical fixed core 310 is housed in the solenoid housing 312 concentrically with the molded coil 314, and the fixed core 310 is extended from the valve housing 301 to a vicinity of a center of the molded coil 314. An end portion of the fixed core 310 on a side opposite with the valve housing 301 is closed by being surrounded by a tubular sleeve 313.

The fixed core 310 has an insertion hole 310 a in a center thereof, and one end of the insertion hole 310 a is opened to the second pressure sensing chamber 307. Furthermore, between the fixed core 310 and a closed end of the sleeve 313, a cylindrical movable core 308 is housed.

A solenoid rod 309 is inserted into the insertion hole 310 a, and one end of the solenoid rod 309 is fixed to a base end side of the valve body 304 by press fitting. Other end portion of the solenoid rod 309 is press-fitted into a through hole formed in the movable core 308, and the solenoid rod 309 and the movable core 308 are integrated with each other. Moreover, between the fixed core 310 and the movable core 308, a forced release spring 311 that urges the movable core 308 in a direction (a valve opening direction) of separating from the fixed core 310 is provided.

The movable core 308, the fixed core 310 and the solenoid housing 312 are formed of a magnetic material, and compose a magnetic circuit. Meanwhile, the sleeve 313 is formed of a non-magnetic material, for example, such as a stainless steel material.

A control device (not illustrated) provided on an outside of the variable displacement compressor 100 is connected to the molded coil 314 via a signal line. Upon being supplied with a control current i from the control device, the molded coil 314 generates electromagnetic force F(i). The electromagnetic force F(i) of the molded coil 314 attracts the movable core 308 toward the fixed core 310, and drives the valve body 304 in a valve closing direction.

On the valve body 304 of the first control valve 300, there act urging force fs by the forced release spring 311, force due to a pressure (a discharge pressure Pd) of the valve chamber 303, force due to a pressure (a crank chamber pressure Pc) of the first pressure sensing chamber 302, force due to a pressure (a suction pressure Ps) of the second pressure sensing chamber 307, and urging force F by the spring incorporated in the bellows 305, as well as the electromagnetic force F(i) by the molded coil 314.

Here, an effective pressure receiving area in an expansion/contraction direction of the bellows 305 is defined as Sb, a receiving area of the pressure of the crank chamber, which acts on the valve body 304 from the valve hole 301 c side, is defined as Sv, a cross-sectional area of the cylindrical outer circumferential surface of the valve body 304 is defined as Sr, and a relationship thereamong is established as Sb=Sv=Sr. Accordingly, a relationship among the forces which act on the valve body 304 is expressed by Equation 1. Note that, in Equation 1, “+” indicates the valve closing direction of the valve body 304, and “−” indicates the valve opening direction thereof.

$\begin{matrix} {{Ps} = {{{- \frac{1}{Sb}} \cdot {F(i)}} + \frac{F + f}{Sb}}} & \left\lbrack {{Equation}\mspace{20mu} 1} \right\rbrack \end{matrix}$

When the pressure of the suction chamber 141 becomes higher than a set pressure, a coupled body of the bellows 305, the coupling portion 306 and the valve body 304 decreases the opening degree of the pressure supply passage 145 and decreases the pressure of the crank chamber 140 in order to increase the discharge displacement. When the pressure of the suction chamber 141 falls down below the set pressure, the coupled body increases the opening degree of the pressure supply passage 145 and raises the pressure of the crank chamber 140 in order to decrease the discharge displacement.

That is, the first control valve 300 autonomously controls the opening degree (the opening area) of the pressure supply passage 145 so that the pressure of the suction chamber 141 can approach the set pressure.

The electromagnetic force of the molded coil 314 acts on the valve body 304 via the solenoid rod 309 in the valve closing direction, and accordingly, when an energization amount to the molded coil 314 increases, force in a direction of decreasing the opening degree of the pressure supply passage 145 increases, and as illustrated in FIG. 3, the set pressure changes in a decreasing direction.

The control device (a drive unit) controls such energization to the molded coil 314 by pulse width modulation (PWM control) at a predetermined frequency, for example, in a range of 400 Hz to 500 Hz, and changes a pulse width (a duty ratio) so that a value of a current flowing through the molded coil 314 can reach a desired value.

When the air conditioning system is in operation, that is, in an operating state of the variable displacement compressor 100, the energization amount to the molded coil 314 is adjusted by the control device based on air conditioning setting such as a set temperature and on an external environment, and the discharge displacement is controlled so that the pressure of the suction chamber 141 can become the set pressure corresponding to the energization amount.

Meanwhile, when the air conditioning system is not in operation, that is, in a non-operating state of the variable displacement compressor 100, the control device turns off the energization to the molded coil 314. In this way, the pressure supply passage 145 is opened by the forced release spring 311, and the discharge displacement of the variable displacement compressor 100 is controlled to a minimum state.

Second Control Valve

FIGS. 4A and 4B are longitudinal sectional views illustrating an example of the second control valve 350 disposed in the cylinder head 104: FIG. 4A illustrates a state of supplying a pressure to the crank chamber 140; and FIG. 4B illustrates a state of releasing the pressure from the crank chamber 140.

The second control valve 350 includes: a housing chamber 104 e, which is formed on an open end surface 104 d side of the cylinder head 104, and is closed by a closing member formed of the discharge valve forming plate 151; the spool 352, which is housed in the housing chamber 104 e, and moves in the axial direction in the housing chamber 104 e; and a partition member 351, which is fixed in the housing chamber 104 e, and partitions the housing chamber 104 e into a first housing chamber (a first space) 104 e 1 and a second housing chamber (a second space) 104 e 2 along the axial direction.

The housing chamber 104 e has: a first valve hole 104 e 32 opened to one end side in a moving direction of the spool 352; and a second valve hole 151 a opened to other end side in the moving direction of the spool 352; and further, a pressure release hole 104 g 1 opened to an inner circumferential wall on the second housing chamber 104 e 2 side of the housing chamber 104 e.

The first valve hole 104 e 32 communicates with a downstream side of the valve hole 301 c of the first control valve 300 via the communication passage 104 f. That is, the first valve hole 104 e 32 communicates with the discharge chamber 142 via the communication passage 104 f, the housing hole 104 b, the first control valve 300 and the communication passage 104 k.

Moreover, the second valve hole 151 a communicates with the crank chamber 140 via the communication hole of the valve plate 103, the communication hole of the suction valve forming plate 150, the communication hole of the cylinder gasket 152, and the communication passage 101 e formed in the cylinder block 101.

Furthermore, the pressure release hole 104 g 1 communicates with the suction chamber 141 via the communication passage 104 g.

Meanwhile, the spool 352 integrally includes: a first valve portion 352 a, which contacts and separates from a first valve seat 104 e 31 provided around the first valve hole 104 e 32; and a second valve portion 352 b, which contacts and separates from a second valve seat 151 b provided around the second valve hole 151 a.

Then, when a pressure of the communication passage 104 f (the pressure supply passage 145 between the first control valve 300 and the second control valve 350) is lower than a pressure of the communication passage 101 e (the crank chamber 140), the spool 352 moves in a right direction of FIG. 4 due to a difference between the pressures, and as illustrated in FIG. 4B, the first valve portion 352 a is seated on the first valve seat 104 e 31, and the second valve portion 352 b separates from the second valve seat 151 b.

Moreover, when the pressure of the communication passage 104 f is higher than the pressure in the communication passage 101 e, the spool 352 moves in a left direction of FIG. 4 due to such a pressure difference, and as illustrated in FIG. 4A, the first valve portion 352 a separates from the first valve seat 104 e 31, and the second valve portion 352 b is seated on the second valve seat 151 b.

Hereinafter, the configuration of the second control valve 350 will be described in more detail.

Housing Chamber and Closing Member

The housing chamber 104 e is formed into a cylindrical shape along an axis parallel to an axis of the drive shaft 110. Moreover, the housing chamber 104 e has: a large diameter portion on the open end surface 104 d side (a side close to the crank chamber 140) of the cylinder head 104; and a small diameter portion smaller in diameter than the large diameter portion on a back side (a far side from the crank chamber 140) thereof. Then, by the partition member 351 fixed to the large diameter portion of the housing chamber 104 e, the small diameter portion composes the first housing chamber 104 e 1, and the large diameter portion composes the second housing chamber 104 e 2.

The first valve seat 104 e 31 on which one end surface (the first valve portion 352 a) of the spool 352 is seated is formed on an end surface 104 e 3 in the axial direction, which composes the first housing chamber 104 e 1, and the first valve hole 104 e 32 is opened on an inside of the first valve seat 104 e 31.

The first valve hole 104 e 32 communicates with a crank chamber pressure area in the housing hole 104 b, which is located downstream of the valve hole 301 c of the first control valve 300, via the communication passage 104 f extended coaxially with the housing chamber 104 e. Moreover, the crank chamber pressure area in the housing hole 104 b, which is located downstream of the valve hole 301 c of the first control valve 300, communicates with the discharge chamber 142 via the first control valve 300 and the communication passage 104 k, and the first valve hole 104 e 32 communicates with the discharge chamber 142 via the pressure supply passage 145 including the communication passage 104 f.

Then, hence, the first housing chamber 101 e 1 composes a part of the pressure supply passage 145, and at the same time, composes a so-called back pressure chamber of the second control valve 350.

Moreover, the communication passage 104 g, which causes the second housing chamber 104 e 2 and the suction chamber 141 to communicate with each other, is connected to a circumferential wall of the second housing chamber 104 e 2, and one end of the communication passage 104 g, which is opened to such an inner circumferential wall of the second housing chamber 104 e 2, composes the pressure release hole 104 g 1.

The second valve hole 151 a is opened in the discharge valve forming plate 151 (the closing member) that closes an open end surface in the axial direction of the second housing chamber 104 e 2, and the second valve seat 151 b on which such other end surface (the second valve portion 352 b) of the spool 352 is seated is formed on the closing member formed around an opening portion of the second valve hole 151 a.

The second housing chamber 104 e 2 communicates with the crank chamber 140 via the second valve hole 151 a, the communication hole of the valve plate 103, the communication hole of the suction valve forming plate 150, the communication hole of the cylinder gasket 152, and the communication passage 101 e formed in the cylinder block 101.

As the closing member that closes the open end surface in the axial direction of the second housing chamber 104 e 2, other compressor constituent members between the cylinder block 101 and the cylinder head 104 can be used in place of the discharge valve forming plate 151, and a dedicated closing member can also be added.

However, if any one of the suction valve forming plate 150, the discharge valve forming plate 151 and the valve plate 103 is used as the closing member, then it is not necessary to add the dedicated closing member, moreover, good accuracy of flatness is brought, and accordingly, any one thereof is suitable as the closing member that forms the valve seat.

Partition Member

The partition member 351 is composed of: a cylindrical side wall 351 a, which is press-fitted into the circumferential wall of the second housing chamber 104 e 2, and partitions the second housing chamber 104 e 2 into an inner cylindrical space and an annular space that communicates with the suction chamber 141; and an end wall 351 b, which partitions the first housing chamber 104 e 1 and the inner cylindrical space of the second housing chamber 104 e 2 from each other, and has an insertion hole 351 b 1 formed in a center portion thereof, the insertion hole 351 b 1 receiving insertion of the spool 352 (a shaft portion 352 c).

In other words, the end wall 351 b separates an annular space around the spool 352 into the first annular space 104 e 1 on the first valve hole 104 e 32 side and the second annular space 104 e 2 on the second valve hole 151 a side, and the pressure release hole 104 g 1 is opened to the second annular space 104 e 2, and causes the suction chamber 141 and the second annular space 104 e 2 to communicate with each other.

The cylindrical space in the inside of the second housing chamber 104 e 2, which is partitioned by the side wall 351 a and the end wall 351 b, compose the valve chamber 351 c.

The partition member 351 is positioned in the second housing chamber 104 e 2 so that an open end surface 351 a 1 of the side wall 351 a can abut against the discharge valve forming plate 151. In the side wall 351 a, there is formed a communication hole 351 a 2 that causes the valve chamber 351 c and the annular space to communicate with each other, the annular space being sandwiched between the side wall 351 a and the inner circumferential wall of the second housing chamber 104 e 2.

Spool

The spool 352 is composed of: the first valve portion 352 a, which is housed in the first housing chamber 101 e 1, and has one end surface 352 a 1 contact and separate from the first valve seat 104 e 31; the second valve portion 352 b, which is housed in the valve chamber 351 c, and has other end surface 352 b 1 (an annular seating surface) contact and separate from the second valve seat 151 b; and the shaft portion 352 c, which is smaller in diameter than the first valve portion 352 a and the second valve portion 352 b, and couples the first valve portion 352 a and the second valve portion 352 b to each other.

The first valve portion 352 a contacts and separates from the first valve seat 104 e 31, thereby opening and closing the first valve hole 104 e 32.

Moreover, the second valve portion 352 b separates from the second valve seat 151 b, whereby a gap (communication portion) 151 b 1 is formed between the second valve portion 352 b and the second valve seat 151 b, and the communication passage 101 e (the second valve hole 151 a) and the communication passage 101 g (the pressure release hole 104 g 1) communicate with each other via such a gap 151 b 1.

Meanwhile, the second valve portion 352 b is seated on the second valve seat 151 b, whereby the gap (communication portion) 151 b 1 between the second valve portion 352 b and the second valve seat 151 b is closed, the communication between the communication passage 101 e (the second valve hole 151 a) and the communication passage 101 g (the pressure release hole 104 g 1) is blocked.

While the shaft portion 352 c is formed as an integral part with the first valve portion 352 a, the second valve portion 352 b is formed as a separate part, and the shaft portion 352 c is press-fitted into the second valve portion 352 b in a state in which the shaft portion 352 c is inserted into the insertion hole 351 b 1 of the partition member 351. In this way, the second valve portion 352 b is fixed to such an integral part of the shaft portion 352 c and the first valve portion 352 a, whereby the spool 352 is composed.

Here, such a press-fitted position of the first valve portion 352 a to the second valve portion 352 b in the axial direction is adjusted so that other end surface 352 a 2 (pressure receiving portion) of the first valve portion 352 a can abut against one end surface 351 b 2 of the end wall 351 b of the partition member 351 in the axial direction simultaneously when the one end surface 352 b 1 of the second valve portion 352 b is seated on the valve seat 151 b provided on the discharge valve forming plate 151.

Note that, if there is adopted such a structure of press-fitting the first valve portion 352 a into the shaft portion 352 c, then as will be described later, since the other end surface 352 a 2 of the first valve portion 352 a composes valve means, it is necessary to form a second communication hole 352 d 3 in consideration of a state in which the first valve portion 352 a is press-fitted into the shaft portion 352 c, and the passage formation becomes complicated. In contrast, if the first valve portion 352 a and the shaft portion 352 c are formed integrally with each other, then it is not necessary to consider deviation of the press-fitted position, and the second communication hole 352 d 3 can be formed with ease.

In the spool 352, there is formed an internal communication passage 352 d composed of: an internal passage 352 d 2, which is opened to the end surface 352 b 1 of the second valve portion 352 b, is extended toward the first valve portion 352 a in the axial direction, and has the first valve portion 352 a side closed; and a first communication hole 352 d 1, which is extended from an outer circumferential surface of the first valve portion 352 a toward an inside thereof in the radial direction, and communicates with an internal passage 352 d 2.

The one end surface (seating surface) 352 b 1 of the second valve portion 352 b is formed into an annular shape in such a manner that the internal passage 352 d 2 is opened.

Moreover, between the other end surface 352 a 2 of the first valve portion 352 a and the one end surface 352 a 1 thereof, the spool 352 is provided with an outermost circumferential surface (sliding contact portion) 352 a 3 slidably supported on an inner circumferential surface of the first housing chamber 101 e 1, and the first communication hole 352 d 1 is provided on the one end surface 352 a 1 side of the outermost circumferential surface (sliding contact portion) 352 a 3.

Furthermore, the second communication hole 352 d 3 is formed, which causes the internal passage 352 d 2 and an outer circumferential surface to communicate with each other, the outer circumferential being located between the other end surface 352 a 2 of the first valve portion 352 a and the outermost circumferential surface 352 a 3 thereof.

Pressure Release Passage and Pressure Supply Passage

As illustrated in FIG. 4B, when the second valve portion 352 b is separated from the second valve seat 151 b, the communication passage 101 e, the communication hole of the cylinder gasket 152, the communication hole of the suction valve forming plate 150, the communication hole of the valve plate 103, the second valve hole 151 a, the gap 151 b 1 between the second valve portion 352 b and the second valve seat 151 b, the valve chamber 351 c, the communication hole 351 a 2, the annular space sandwiched between the side wall 351 a and the inner circumferential wall of the second housing chamber 104 e 2, the pressure release hole 104 g 1 and the communication passage 104 g compose the first pressure release passage 146 b that causes the crank chamber 140 and the suction chamber 141 to communicate with each other, and the refrigerant in the crank chamber 140 is discharged to the suction chamber 141 via such a first pressure release passage 146 b as described above.

That is, the second valve portion 352 b is separated from the second valve seat 151 b, whereby the gap 151 b 1 is formed between the second valve portion 352 b and the second valve seat 151 b, the communication portion between the communication passage 101 e and the communication passage 104 g is opened, the opening degree of the first pressure release passage 146 b becomes the maximum opening degree, and the refrigerant in the crank chamber 140 is discharged to the suction chamber 141.

Moreover, when the second valve portion 352 b is separated from the second valve seat 151 b, the first valve portion 352 a is seated on the first valve seat 104 e 31, the first valve hole 104 e 32 is closed, and the pressure supply passage 145 composed by including the first valve hole 104 e 32 is closed.

Meanwhile, as illustrated in FIG. 4A, when the second valve portion 352 b is seated on the second valve seat 151 b, the gap 151 b 1 between the second valve portion 352 b and the second valve seat 151 b, that is, the communication portion between the communication passage 101 e and the communication passage 104 g is closed, whereby the first pressure release passage 146 b including the gap 151 b 1 is closed. Hence, by the fact that the second valve portion 352 b is seated on the second valve seat 151 b, the fixed throttle 103 c of the second pressure release passage 146 a in the pressure release passage 146 turns to a minimum opening, and the refrigerant in the crank chamber 140 is restricted from being discharged to the suction chamber 141.

Here, when the second valve portion 352 b is seated on the second valve seat 151 b, then the first valve portion 352 a is separated from the first valve seat 104 e 31, and the first valve hole 104 e 32 is opened.

In this way, the communication passage 104 k, the first control valve 300, the housing hole 104 b, the communication passage 104 f, the first valve hole 104 e 32, the first housing chamber (a first space) 104 e 1, the first communication hole 352 d 1, the internal passage 352 d 2, the second valve hole 151 a, the communication hole of the valve plate 103, the communication hole of the suction valve forming plate 150, the communication hole of the cylinder gasket 152 and the communication passage 101 e compose the pressure supply passage 145 that causes the crank chamber 140 and the discharge chamber 142 to communicate with each other, and the refrigerant in the discharge chamber 142 is supplied to the crank chamber 140 via the pressure supply passage 145.

As described above, the second valve hole 151 a, the communication hole of the valve plate 103, the communication hole of the suction valve forming plate 150, the communication hole of the cylinder gasket 152 and the communication passage 101 e also serve as the first pressure release passage 146 b and the pressure supply passage 145, and a flow direction of the refrigerant in the communication passage 101 e is reversed between when the pressure is released from the crank chamber 140 and when the pressure is supplied to the crank chamber 140.

In other words, the communication passage that causes the second valve hole 151 a and the crank chamber 140 to communicate with each other is switched, in response to the position of the spool 352, between a state in which the communication passage concerned composes a part of the first pressure release passage 146 b and a state in which the communication passage concerned composes a part of the pressure supply passage 145.

When the second valve portion 352 b is seated on the second valve seat 151 b, and the first valve portion 352 a is separated from the first valve seat 104 e 31, then the refrigerant flows from the second valve hole 151 a toward the crank chamber 140 through the communication passage 101 e, which causes the second valve hole 151 a and the crank chamber 140 to communicate with each other, and the communication passage 101 e functions as the pressure supply passage 145.

Meanwhile, when the second valve portion 352 b is separated from the second valve seat 151 b, and the first valve portion 352 a is seated on the first valve seat 104 e 31, then the refrigerant flows from the crank chamber 140 toward the second valve hole 151 a through the communication passage 101 e, which causes the second valve hole 151 a and the crank chamber 140 to communicate with each other, and the communication passage 101 e functions as the first pressure release passage 146 b.

Note that a minute gap is formed between the outermost circumferential surface 352 a 3 of the first valve portion 352 a of the spool 352 and the inner circumferential surface of the first housing chamber 104 e 1.

Therefore, in a state in which the one end surface 352 a 1 of the first valve portion 352 a is slightly separated from the first valve seat 104 e 31, the refrigerant gas, which has flown into the first housing chamber 104 e 1 from the communication passage 104 f, flows into the valve chamber 351 c (the second housing chamber 104 e 2) via a gap between the outermost circumferential surface 352 a 3 and the inner circumferential surface of the first housing chamber 104 e 1 and a gap between the outer circumferential surface of the shaft portion 352 c and the inner circumferential surface of the insertion hole 351 b 1.

Meanwhile, a configuration is adopted so that the other end surface 352 a 2 of the first valve portion 352 a can abut against the one end surface 351 b 2 of the end wall 351 b in a state in which the end surface 352 b 1 of the second valve portion 352 b is seated on the second valve seat 151 b and the one end surface 352 a 1 of the first valve portion 352 a is separated from the first valve seat 104 e 31 to the maximum. Accordingly, the flow of the refrigerant from the first housing chamber 104 e 1 to the valve chamber 351 c, the flow passing via the gap between the outer circumferential surface of the shaft portion 352 c and the inner circumferential surface of the insertion hole 351 b 1, is blocked.

That is, the other end surface 352 a 2 of the first valve portion 352 a and the one end surface 351 b 2 of the end wall 351 b compose valve means (a valve device) for blocking the flow of the refrigerant from the first housing chamber 104 e 1 to the valve chamber 351 c, the flow passing via the gap between the outer circumferential surface of the shaft portion 352 c and the inner circumferential surface of the insertion hole 351 b 1.

Hence, when the first housing chamber 101 e 1 functions as the pressure supply passage 145, the refrigerant is suppressed from flowing out from the first housing chamber 101 e 1 to the suction chamber 141 via the valve chamber 351 c, and most of the refrigerant gas, which has flown into the first housing chamber 101 e 1, can be supplied to the crank chamber 140.

Note that, in the spool 352, there is formed the second communication hole 352 d 3, in which one end is opened between the other end surface 352 a 2 of the first valve portion 352 a of the spool 352 and the outermost circumferential surface 352 a 3 thereof, and other end is opened to the inner passage 352 d 2 as a result of extending the second communication hole 352 d 3 concerned from such an opening portion in the radial direction.

Therefore, the refrigerant gas, which has flown into the gap between the outermost circumferential surface 352 a 3 of the first valve portion 352 a and the inner circumferential surface of the first housing chamber 104 e 1, flows into the internal passage 352 d 2 via the second communication hole 352 d 3, and merges into the refrigerant that has flown into the internal passage 352 d 2 via the first communication hole 352 d 1.

The refrigerant gas sometimes contains minute contaminants. Although the gap between the outermost circumferential surface 352 a 3 of the first valve portion 352 a and the inner circumferential surface of the first housing chamber 104 e 1 has an opening area sufficient for causing the contaminants to pass therethrough, since the second communication hole 352 d 3 is formed, the refrigerant gas is enabled to flow through the gap between the outermost circumferential surface 352 a 3 of the first valve portion 352 a and the inner circumferential surface of the first housing chamber 104 e 1, so that the contaminants are suppressed from being accumulated in the gap. In this way, the movement of the spool 352 can be suppressed from being hindered by the accumulation of the contaminants.

Moreover, by the contact between the other end surface 352 a 2 of the first valve portion 352 a and the one end surface 351 b 2 of the end wall 351 b, leakage through the gap between the outer circumferential surface of the shaft portion 352 c and the inner circumferential surface of the insertion hole 351 b 1 is suppressed, and accordingly, the configuration of the valve means for suppressing the leakage is simple.

Throttle Passage

A region of the pressure supply passage 145 between the first control valve 300 and the second control valve 350 communicates with the suction chamber 141 via a throttle passage 104 h. Since the throttle passage 104 h has a throttle, the amount of the refrigerant flowing out from the pressure supply passage 145 to the suction chamber 141 via the throttle passage 104 h is small.

Hence, when the first control valve 300 closes, and further, the one end surface 352 a 1 of the first valve portion 352 a is seated on the first valve seat 104 e 31 to close the pressure supply passage 145, then the back pressure Pm that acts on the one end surface of the spool 352 becomes equivalent to the pressure of the suction chamber 141.

Moreover, when the first control valve 300 opens, and further, the one end surface 352 a 1 of the first valve portion 352 a is separated from the first valve seat 104 e 31 to open the pressure supply passage 145, then the back pressure Pm that acts on the one end surface of the spool 352 becomes higher than the pressure of the suction chamber 141.

Operation of Spool

One end surface (the one end surface 352 a 1 of the first valve portion 352 a) of the spool 352 receives the pressure of the pressure supply passage 145 on an upstream side (between the first control valve 300 and the second control valve 350) thereof, that is, a so-called back pressure Pm.

Meanwhile, other end surface (the one end surface 352 b 1 of the second valve portion 352 b) of the spool 352 receives the pressure Pc of the crank chamber 140. Then, the spool 352 moves in the axial direction in response to a pressure difference ΔP (ΔP=Pm−Pc) between the back pressure Pm and the pressure Pc.

When the first control valve 300 opens, and the back pressure Pm of the spool 352 becomes higher than the pressure Pc of the crank chamber 140 (that is, in a state of Pm−Pc>0), the one end surface 352 b 1 of the second valve portion 352 b of the spool 352 is seated on the second valve seat 151 b, and closes the communication portion 151 b 1 between the communication passage 104 g and the communication passage 101 e. Simultaneously, the one end surface 352 a 1 of the first valve portion 352 a is separated from the first valve seat 104 e 31, and the communication passage (the pressure supply passage 145) between the discharge chamber 142 and the crank chamber 140 is opened.

That is, when the first control valve 300 opens, then the first valve portion 352 a is separated from the first valve seat 104 e 31, and the first valve hole 104 e 32 is opened, and the refrigerant in the discharge chamber 142 is supplied to the crank chamber 140 via the pressure supply passage 145 composed of the communication passage 104 k, the first control valve 300, the housing hole 104 b, the communication passage 104 f, the first valve hole 104 e 32, the first housing chamber (the first space) 104 e 1, the first communication hole 352 d 1, the internal passage 352 d 2, the second valve hole 151 a, the communication hole of the valve plate 103, the communication hole of the suction valve forming plate 150, the communication hole of the cylinder gasket 152 and the communication passage 101 e.

In this way, only the second pressure release passage 146 a between the second pressure release passage 146 a and the first pressure release passage 146 b is opened, and a minimum opening area of the pressure release passage 146 becomes an opening area of the fixed throttle 103 c. Therefore, the pressure of the crank chamber 140 becomes easy to rise, the pressure in the crank chamber 140 rises in response to the opening degree of the first control valve 300, the inclination angle of the swash plate 111 decreases from the maximum, and the piston stroke can be controlled variably.

Meanwhile, when the first control valve 300 closes, and the back pressure Pm of the spool 352 becomes lower than the pressure Pc of the crank chamber 140 (that is, in a state of Pm−Pc<0), then the one end surface 352 a 1 of the first valve portion 352 a is seated on the first valve seat 104 e 31, and closes the first valve hole 104 e 32 (the pressure supply passage 145). Simultaneously, the one end surface 352 b 1 of the second valve portion 352 b of the spool 352 is separated from the second valve seat 151 b, an opening degree (an opening area) of the communication portion 151 b 1 between the communication passage 104 g and the communication passage 101 e becomes the maximum opening degree, and the opening degree of the first pressure release passage 146 b between the crank chamber 140 and the suction chamber 141 becomes the maximum opening degree.

That is, when the first control valve 300 closes, then the second valve portion 352 b is separated from the second valve seat 151 b, the communication portion 151 b 1 is opened, and the refrigerant in the crank chamber 140 is discharged to the suction chamber 141 via the first pressure release passage 146 b and the second pressure release passage 146 a, which are composed of the communication passage 101 e, the communication hole of the cylinder gasket 152, the communication hole of the suction valve forming plate 150, the communication hole of the valve plate 103, the second valve hole 151 a, the communication portion 151 b 1, the valve chamber 351 c, the communication hole 351 a 2, the annular space sandwiched between the side wall 351 a and the inner circumferential wall of the second housing chamber (a second space) 104 e 2, the pressure release hole 104 g 1 and the communication passage 104 g.

In this way, the supply of the refrigerant from the discharge chamber 142 to the crank chamber 140 is stopped, and meanwhile, the refrigerant in the crank chamber 140 is rapidly discharged to the suction chamber 141 via the second pressure release passage 146 a (the fixed throttle 103 c) and the first pressure release passage 146 b. Therefore, the pressure of the crank chamber 140 becomes equivalent to the pressure of the suction chamber 141, the inclination angle of the swash plate becomes the maximum, and the piston stroke (the discharge displacement) becomes the maximum.

At this time, the first valve portion 352 a is seated on the first valve seat 104 e 31 and closes the first valve hole 104 e 32, and accordingly, the refrigerant is hindered from flowing backward to the first control valve 300 side via the first valve hole 104 e 32 (the pressure supply passage 145).

Note that a pressure receiving area S1 of the spool 352 in the axial direction, which receives the back pressure Pm, and a pressure receiving area S2 of the spool 352, which receives the pressure Pc of the crank chamber 140, are set, for example, to S1=S2; however, can be set to S1>S2 or S1<S2 in order to adjust the operation of the spool 352.

As described above, the second control valve 350 is provided with a function to control the opening degree of the pressure release passage 146 to the minimum opening degree by closing the first pressure release passage 146 b when the first control valve 300 opens, and to control the opening degree of the first pressure release passage 146 b to the maximum opening degree when the first control valve 300 closes, and simultaneously, is provided with a function as a check valve that blocks the flow of the refrigerant directed from the crank chamber 140 toward the first control valve 300 when the first control valve 300 closes.

Hence, in the variable displacement compressor 100, a structure thereof is simpler and a valve layout thereof is easier in comparison with such a case of separately providing a control valve that opens and closes the first pressure release passage 146 b in response to the opening and closing of the first control valve 300 and a check valve that blocks the reverse flow of the refrigerant directed toward the first control valve 300.

Operation of Variable Displacement Compressor

When the energization to the molded coil 314 of the first control valve 300 is interrupted in a state in which the variable displacement compressor 100 is in operation, the opening area of the first control valve 300 is maximized, the pressure supply passage 145 is opened, and the back pressure Pm of the spool 352 of the second control valve 350 rises.

Therefore, when the one end surface 352 a 1 of the first valve portion 352 a is seated on the first valve seat 104 e 31 (in the maximum discharge displacement state), the spool 352 moves in a direction of approaching the crank chamber 140 (the second valve seat 151 b), and the one end 352 a 1 of the first valve portion 352 a is separated from the first valve seat 104 e 31, and simultaneously, the one end surface 352 b 1 of the second valve portion 352 b is seated on the second valve seat 151 b, and closes the communicating portion 151 b 1 (the first pressure release passage 146 b) between the communication passage 104 g and the communication passage 101 e.

That is, when the first control valve 300 opens, the pressure release passage 146 becomes only the second pressure release passage 146 a (the opening area of the pressure release passage is minimized), and meanwhile, the pressure supply passage 145 that causes the discharge chamber 142 and the crank chamber 140 to communicate with each other is opened. As a result, the pressure of the crank chamber 140 rises, the inclination angle of the swash plate 111 decreases, and the discharge displacement is changed to the minimum and is maintained.

As mentioned above, such a dynamic pressure of the refrigerant flowing through the pressure supply passage 145 acts on the spool 352, whereby the one end surface 352 b 1 of the second valve portion 352 b is seated on the second valve seat 151 b. In such a seated state of the second valve portion 352 b, such a dynamic pressure of pressing the first pressure release passage 146 b in a direction of opening the same does not act on the second valve portion 352 b, and the closed state of the first pressure release passage 146 b (that is, a state of the minimum opening degree of the pressure release passage 146) can be maintained stably.

Moreover, in the closed state of the first pressure release passage 146 b, the pressure release is performed via the second pressure release passage 146 a, and accordingly, it is possible to dispose the second pressure release passage 146 a appropriately in consideration of lubrication and the like without being bound by the position of the second control valve 350.

In such a minimum discharge displacement state, the discharge check valve 200 shuts off the connection portion (discharge passage) between the communication passage 144 and the muffler space 143, and the refrigerant gas discharged with the minimum discharge displacement does not flow to the external refrigerant circuit, but circulates through an internal circulation passage composed of the discharge chamber 142, the pressure supply passage 145, the crank chamber 140, the second pressure release passage 146 a, the suction chamber 141 and the cylinder bore 101 a. At this time, the refrigerant of the pressure supply passage 145 between the first control valve 300 and the second control valve 350 slightly flows out to the suction chamber 141 via the throttle passage 104 h.

When the molded coil 314 of the first control valve 300 is energized from this state (the minimum discharge displacement state), the first control valve 300 closes, and the pressure supply passage 145 is closed. Hence, the refrigerant in the pressure supply passage 145 between the first control valve 300 and the second control valve 350 flows out into the suction chamber 141 via the throttle passage 104 h, and the pressure (the back pressure Pm) of the pressure supply passage 145 between the first control valve 300 and the second control valve 350 decreases.

In response to such a decrease of the back pressure Pm, the spool 352 moves in a direction of going away from the crank chamber 140 (the second valve seat 151 b), whereby the first valve portion 352 a is seated on the first valve seat 104 e 31 to close the first valve hole 104 e 32 (the pressure supply passage 145). Accordingly, the refrigerant is hindered from flowing backward from the crank chamber 140 via the communication passage 101 e to the pressure supply passage 145 located upstream of the second control valve 350. Simultaneously, the one end surface 352 b 1 of the second valve portion 352 b is separated from the second valve seat 151 b, whereby the communication portion 151 b 1 (the first pressure release passage 146 b) between the communication passage 104 g and the communication passage 101 e is opened.

As described above, by the movement of the spool 352 due to such a pressure difference between the front and back thereof, the opening degree of the first pressure release passage 146 b can be switched with ease between the maximum opening degree (the open state) and the minimum opening degree (the closed state).

Note that, when the first valve portion 352 a includes urging means (an elastic member, a spring or the like) for urging the spool 352 in a direction of being seated on the first valve seat 104 e 31, when the air conditioning system is driven in a state in which the variable displacement compressor 100 is not operated, and the pressure difference between the discharge chamber 142 and the suction chamber 141 becomes extremely small, then there is a possibility that the state of the variable displacement compressor 100 may suddenly turn to state in which the pressure supply passage is closed and the first pressure release passage 146 b is opened by urging force of the urging means, and the discharge displacement may increase rapidly and abruptly.

In contrast, the variable displacement compressor 100 of this embodiment does not include the urging means for urging the spool 352, and the spool 352 moves in response to the pressure difference between the front and back thereof. Accordingly, even if the pressure difference between the discharge chamber 142 and the suction chamber 141 becomes extremely small, there can be suppressed such a phenomenon that the discharge displacement is increased rapidly and abruptly by the fact that the state of the variable displacement compressor 100 turns to the state in which the pressure supply passage is closed and the first pressure release passage 146 b is opened.

When the molded coil 314 is energized to close the first control valve 300, the opening degree of the first pressure release passage 146 b becomes the maximum opening degree, and the refrigerant of the crank chamber 140 is discharged into the suction chamber 141 via the two pressure release passages 146 a and 146 b.

The flow passage cross-sectional area of the first pressure release passage 146 b in the second control valve 350 is set larger than the flow passage cross-sectional area of the fixed throttle 103 c (the second pressure release passage 146 a). Accordingly, when the opening degree of the first pressure release passage 146 b is controlled to the maximum opening degree by the second control valve 350, the refrigerant in the crank chamber 140 quickly flows into the suction chamber 141, the pressure of the crank chamber 140 decreases, and the discharge displacement quickly increases from the state of the minimum to the maximum discharge displacement.

In this way, the pressure of the discharge chamber 142 rises suddenly to open the discharge check valve 200, the refrigerant gas is discharged from the variable displacement compressor 100, the refrigerant circulates through the external refrigerant circuit, and the air conditioning system turns to an operating state.

When the air conditioning system operates, and the pressure in the suction chamber 141 decreases and reaches the set pressure set by the current flowing through the molded coil 314, then the first control valve 300 opens. When the first control valve 300 opens, the back pressure Pm of the spool 352 of the second control valve 350 rises, and accordingly, the second control valve 350 opens the pressure supply passage 145, and at the same time, closes the first pressure release passage 146 b.

At this time, only the second pressure release passage 146 a between the pressure release passages 146 a and 146 b is opened. In this way, the refrigerant in the crank chamber 140 is restricted from flowing out into the suction chamber 141, the pressure of the crank chamber 140 becomes easy to rise, the opening degree of the first control valve 300 is adjusted so that the pressure of the suction chamber 141 can maintain the set pressure, and the discharge displacement is variably controlled.

That is, the second control valve 350 operates in conjunction with the opening and closing of the first control valve 300, when the first control valve 300 closes, the opening degree of the first pressure release passage 146 b is set to the maximum opening degree, and when the first control valve 300 is opened, the opening degree of the first pressure release passage 146 b is set to the minimum opening degree.

Second Embodiment

In the first embodiment illustrated in FIG. 1 to FIG. 4, the second valve portion 352 b of the spool 352 is seated on the second valve seat 151 b, thereby closing the communication portion 151 b 1 (the first pressure release passage 146 b) between the communication passage 104 g and the communication passage 101 e. However, such a configuration can be adopted, in which, when the second valve portion 352 b is seated on the second valve seat 151 b, a gap is formed in a part of a mating surface between the second valve portion 352 b and the second valve seat 151 b, and the pressure is released via this gap (that is, the refrigerant is discharged from the crank chamber 140 to the suction chamber 141).

FIGS. 5A and 5B illustrate a second embodiment of the variable displacement compressor 100, which is configured so that the pressure can be released via the first pressure release passage 146 b in a state in which the second valve portion 352 b of the spool 352 is seated on the second valve seat 151 b: FIG. 5A illustrates a state of supplying the pressure to the crank chamber 140, and FIG. 5B illustrates a state of releasing the pressure from the crank chamber 140.

In such a second control valve 350 illustrated in FIGS. 5A and 5B, a notch groove portion 352 b 3 (a throttle passage) extended in the radial direction is formed on the end surface 352 b 1 (the annular seating surface) of the second valve portion 352 b.

Note that the configuration of the second embodiment is the same as that of the first embodiment illustrated in FIGS. 1 to 4 except that the notch groove portion 352 b 3 is added, and a detailed description of common portions will be omitted.

In the second control valve 350 in which the notch groove portion 352 b 3 is formed on the end surface 352 b 1 of the second valve portion 352 b, the internal passage 352 d 2 and the valve chamber 351 c communicate with each other via the notch groove portion 352 b 3 when the second valve portion 352 b is seated on the second valve seat 151 b. In this way, the communication passage 101 e and the communication passage 104 g communicate with each other, and the refrigerant in the crank chamber 140 is discharged into the suction chamber 141 via the notch groove portion 352 b 3.

That is, the minimum opening degree of the communication portion 151 b 1 between the communication passage 101 e and the communication passage 104 g, in other words, the minimum opening degree of the first pressure release passage 146 b becomes an opening area of the notch groove portion 352 b 3, and even when the second valve portion 352 b is seated on the second valve seat 151 b, the first pressure release passage 146 b is not closed, but opens by the minimum opening degree that coincides with a cross-sectional area of the notch groove portion 352 b 3.

In this way, the refrigerant in the crank chamber 140 flows out into the suction chamber 141 via the first pressure release passage 146 b composed of the communication passage 101 e, the communication hole of the cylinder gasket 152, the communication hole of the suction valve forming plate 150, the communication hole of the valve plate 103, the second valve hole 151 a, the notch groove portion 352 b 3, the valve chamber 351 c, the communication hole 351 a 2, the annular space sandwiched between the side wall 351 a and the inner circumferential wall of the second housing chamber (the second space) 104 e 2, the pressure release hole 104 g 1 and the communication passage 104 g.

Hence, if a cross-sectional area of the notch groove portion 352 b 3 is made equivalent to the opening area of the fixed throttle 103 c of the second pressure release passage 146 a in the first embodiment, then the first pressure release passage 146 b also has the function of the second pressure release passage 146 a, and the second pressure release passage 146 a can be omitted.

Third Embodiment

In the above-described first and second embodiments, the passage portion, which is composed of the second valve hole 151 a, the communication hole of the valve plate 103, the communication hole of the suction valve forming plate 150, the communication hole of the cylinder gasket 152, and the communication passage 101 e, also serves as the first pressure release passage 146 b and the pressure supply passage 145; however, the first pressure release passage 146 b and the pressure supply passage 145 can be provided as separate routes.

FIG. 6 illustrates such a second control valve 350 of a third embodiment, in which only a passage portion composed of the second valve hole 151 a, the communication hole of the valve plate 103, the communication hole of the suction valve forming plate 150, the communication hole of the cylinder gasket 152 and the communication passage 101 e is used only as the first pressure release passage 146 b, and a pressure supply passage that supplies the refrigerant from the second control valve 350 to the crank chamber 140 is provided separately.

Note that FIG. 6 is a cross-sectional view when the second control valve 350 opens the pressure supply passage 145.

In the second control valve 350 illustrated in FIG. 6, a pressure supply hole 104 j is opened at a position where the second valve portion 352 b does not overlap the outermost circumferential surface 352 a 3 at a time of being seated on the second valve seat 151 b, the position belonging to the inner circumferential wall of the first housing chamber 104 e 1 of the housing chamber 104 e, and a communication passage 104 m is formed, in which one end communicates with this pressure supply hole 104 j, and other end communicates with the crank chamber 140.

The communication passage 104 m, which communicates with the first housing chamber 104 e 1 and the crank chamber 140, is composed of: a communication passage 104 m 1 formed in the cylinder head 104; a communication hole of the discharge valve forming plate 151; the communication hole of the valve plate 103; the communication hole of the suction valve forming plate 150; the communication hole of the cylinder gasket 152; and a communication passage 104 m 2 formed in the cylinder block 101.

Moreover, a communication hole 352 d 4, which causes the first housing chamber (the first space) 104 e 1 and the communication passage 104 m (the communication passage 104 m 1) to communicate with each other, is formed, the first housing chamber 104 e 1 being formed between the outermost circumferential surface 352 a 3 and the partition member 351.

Meanwhile, the internal passage 352 d 2, the first communication hole 352 d 1 and the second communication hole 352 d 2, which are formed in the first and second embodiments, are not formed in the spool 352.

The second control valve 350 of the third embodiment is different from the second control valve 350 of the first embodiment in that the second control valve 350 of the third embodiment includes the communication passage 104 m and the communication hole 352 d 4, and does not include the internal passage 352 d 2, the first communication hole 352 d 1 and the second communication hole 352 d 2. However, except for the above, the second control valve 350 of the third embodiment has a same configuration as that of the second control valve 350 of the first embodiment illustrated in FIG. 1 to FIG. 4, and a detailed description of common portions will be omitted.

In the second control valve 350 of the third embodiment, when the first control valve 300 opens, the first valve portion 352 a is separated from the first valve seat 104 e 31, and the second valve portion 352 b is seated on the second valve seat 151 b, then the first valve hole 104 e 32 opens, and the refrigerant in the discharge chamber 142 is supplied to the crank chamber 140 via the pressure supply passage 145 composed of: the communication passage 104 k; the first control valve 300; the housing hole 104 b; the communication passage 104 f; the first valve hole 104 e 32; the first housing chamber (the first space) 104 e 1; the pressure supply hole 104 j; the communication passage 104 m 1; the communication hole of the discharge valve forming plate 151; the communication hole of the valve plate 103; the communicating hole of the suction valve forming plate 150; the communication hole of the cylinder gasket 152; and the communication passage 104 m 2.

Moreover, when the first control valve 300 closes, the first valve portion 352 a is seated on the first valve seat 104 e 31, and the second valve portion 352 b is separated from the second valve seat 151 b, then the pressure supply passage 145 composed by including the communication passage 104 m is closed in such a manner that the first valve hole 104 e 32 is closed, and the reverse flow of the refrigerant directed toward the first control valve 300 is blocked, and meanwhile, the communication portion 151 b 1 between the communication passage 101 e and the communication passage 104 g opens.

In this way, the opening degree of the first pressure release passage 146 b becomes the maximum opening degree, the first pressure release passage 146 b being composed of: the communication passage 101 e; the communication hole of the cylinder gasket 152; the communication hole of the suction valve forming plate 150; the communication hole of the valve plate 103; the second valve hole 151 a; the gap (the communication portion) 151 b 1 between the second valve portion 352 b and the second valve seat 151 b; the valve chamber 351 c; the communication hole 351 a 2; the annular space in the second housing chamber (the second space) 104 e 2 on the outside of the side wall 351 a; the pressure release hole 104 g 1; and the communication passage 104 g. Then, the refrigerant in the crank chamber 140 is discharged into the suction chamber 141 via the second pressure release passage 146 a and the first pressure release passage 146 b.

As described above, in a similar way to the second control valves 350 of the first and second embodiments, the second control valve 350 of the third embodiment also combines the function to open and close the first pressure release passage 146 b in response to the opening and closing of the first control valve 300 and the function to block the reverse flow of the refrigerant toward the first control valve 300. Accordingly, in the second control valve 350 of the third embodiment, a structure thereof is simpler and a valve layout thereof is easier in comparison with such a case of separately providing the control valve that opens and closes the first pressure release passage 146 b in response to the opening and closing of the first control valve 300 and the check valve that blocks the reverse flow of the refrigerant directed toward the first control valve 300.

Moreover, the refrigerant gas that has flown into the gap between the outermost circumferential surface 352 a 3 of the first valve portion 352 a and the inner circumferential surface of the first housing chamber 104 e 1 flows into the communication passage 104 m (the communication passage 104 m 1) via the communication hole 352 d 4, and merges into the refrigerant flowing through the inside of the communication passage 104 m.

In this way, the refrigerant gas is caused to flow into the gap between the outermost circumferential surface 352 a 3 of the first valve portion 352 a and the inner circumferential surface of the first housing chamber 104 e 1, and the accumulation of the contaminants in the gap is suppressed. In a similar way to the second control valves 350 of the first and second embodiments, the movement of the spool 352 can be suppressed from being hindered by the accumulation of the contaminants.

Fourth Embodiment

In the second control valve 350 of the third embodiment illustrated in FIG. 6, the second valve portion 352 b of the spool 352 is seated on the second valve seat 151 b, thereby closing the communication portion 151 b 1 (the first pressure release passage 146 b) between the communication passage 104 g and the communication passage 101 e. However, such a configuration can be adopted, in which, when the second valve portion 352 b is seated on the second valve seat 151 b, a gap is formed in a part of a mating surface between the second valve portion 352 b and the second valve seat 151 b, and the pressure is released via this gap (that is, the refrigerant is discharged from the crank chamber 140 to the suction chamber 141).

FIG. 7 illustrates a fourth embodiment of the variable displacement compressor 100, in which the first pressure release passage 146 b and the pressure supply passage 145 are provided as separate routes, and the pressure is released via the first pressure release passage 146 b in a state in which the second valve portion 352 b of the spool 352 is seated on the second valve seat 151 b.

Note that FIG. 7 is a cross-sectional view when the second control valve 350 opens the pressure supply passage 145.

In the second control valve 350 illustrated in FIG. 7, such a notch groove portion 352 b 3 (the throttle passage) extended in the radial direction is formed on the end surface 352 b 1 (the annular seating surface) of the second valve portion 352 b.

Note that the second control valve 350 of the fourth embodiment is similar to that of the third embodiment in that the communication passage 104 m and the communication hole 352 d 4 are provided, and that the internal passage 352 d 2, the first communication hole 352 d 1 and the second communication hole 352 d 2 are not provided, and is different from the second control valve 350 of the third embodiment in that the notch groove portion 352 b 3 is added.

As described above, in the second control valve 350 in which the notch groove portion 352 b 3 is formed on the end surface 352 b 1 of the second valve portion 352 b, the communication passage 101 e and the communication passage 104 g communicate with each other via the notch groove portion 352 b 3 when the second valve portion 352 b is seated on the second valve seat 151 b, and the refrigerant in the crank chamber 140 is discharged into the suction chamber 141 via the notch groove portion 352 b 3.

That is, the minimum opening degree of the communication portion 151 b 1 between the communication passage 101 e and the communication passage 104 g, in other words, the minimum opening degree of the first pressure release passage 146 b becomes such an opening area of the notch groove portion 352 b 3, and even when the second valve portion 352 b is seated on the second valve seat 151 b, the first pressure release passage 146 b is not closed, but opens by the minimum opening degree that coincides with a cross-sectional area of the notch groove portion 352 b 3.

In this way, the refrigerant in the crank chamber 140 flows out into the suction chamber 141 via the first pressure release passage 146 b composed of the communication passage 101 e, the communication hole of the cylinder gasket 152, the communication hole of the suction valve forming plate 150, the communication hole of the valve plate 103, the second valve hole 151 a, the notch groove portion 352 b 3, the valve chamber 351 c, the communication hole 351 a 2, the annular space sandwiched between the side wall 351 a and the inner circumferential wall of the second housing chamber (the second space) 104 e 2, the pressure release hole 104 g 1 and the communication passage 104 g.

Hence, if such a cross-sectional area of the notch groove portion 352 b 3 is made equivalent to the opening area of the fixed throttle 103 c of the second pressure release passage 146 a, then the first pressure release passage 146 b also has the function of the second pressure release passage 146 a, and the second pressure release passage 146 a can be omitted.

As above, the specific description has been made of the contents of the present invention with reference to the preferred embodiments; however, it is self-evident that those skilled in the art can adopt a variety of modified forms based on the basic technical idea and teaching of the present invention.

For example, a structure can be adopted, in which, when the first valve portion 352 a of the spool 352 is seated on the first valve seat 104 e 31, leakage is allowed within a range that does not hinder the reduction of the back pressure Pm.

Moreover, in each of the above-described embodiments, the second control valve 350 is disposed in the cylinder head 104; however, the second control valve 350 can be disposed in other members, each of which composes the housing, for example, the cylinder block, or alternatively, the second control valve 350 can be housed in a valve housing dedicated thereto, and can be disposed in the compressor housing.

Moreover, a mechanical control valve that does not include such a solenoid can be used as the first control valve 300.

Moreover, in each of the above-described embodiments, the variable displacement compressor 100 is defined to be the swash plate-type clutchless variable displacement compressor. However, the present invention is not limited to this, and the variable displacement compressor 100 can be defined to a variable displacement compressor equipped with an electromagnetic clutch or a variable displacement compressor driven by a motor.

REFERENCE SYMBOL LIST

-   100 variable displacement compressor -   101 cylinder block -   101 e communication passage -   102 front housing -   103 valve plate -   104 cylinder head -   104 b housing hole -   104 e housing chamber -   104 e 1 first housing chamber (first space) -   104 e 2 second housing chamber (second space) -   104 e 32 first valve hole -   104 f communication passage -   104 g communication passage -   104 g 1 pressure release hole -   104 k communication passage -   104 j pressure supply hole -   104 m communication passage -   110 drive shaft -   140 crank chamber -   141 suction chamber -   142 discharge chamber -   145 pressure supply passage -   146 a second pressure release passage -   146 b first pressure release passage -   150 suction valve forming plate -   151 a second valve hole -   151 b 1 communication portion -   152 cylinder gasket -   300 first control valve -   350 second control valve -   351 partition member -   351 c valve chamber -   351 a 2 communication hole -   352 spool -   352 a first valve portion -   352 b second valve portion -   352 d 1 first communication hole -   352 d 2 internal passage 

1. A variable displacement compressor in which a discharge displacement is controlled by pressure regulation in a crank chamber, comprising: a first control valve that controls an opening degree of a pressure supply passage that causes a discharge chamber and the crank chamber to communicate with each other; and a second control valve including a spool having a first valve portion that opens and closes the pressure supply passage between the first control valve and the crank chamber and a second valve portion that opens and closes a pressure release passage that causes the crank chamber and a suction chamber to communicate with each other, wherein the spool moves in response to a difference between a pressure of the pressure supply passage between the first control valve and the second control valve and a pressure of the crank chamber, when the pressure of the pressure supply passage between the first control valve and the second control valve is higher than the pressure of the crank chamber, the first valve portion opens the pressure supply passage to supply a fluid from the discharge chamber to the crank chamber, and the second valve portion sets an opening degree of the pressure release passage to a minimum opening degree, and when the pressure of the pressure supply passage between the first control valve and the second control valve is lower than the pressure of the crank chamber, the first valve portion closes the pressure supply passage to block a reverse flow of the fluid directed from the crank chamber toward the first control valve, and the second valve portion sets the opening degree of the pressure release passage to a maximum opening degree.
 2. The variable displacement compressor according to claim 1, wherein a housing chamber that houses the spool therein has: a first valve hole that opens to one end side in a moving direction of the spool and communicates with the discharge chamber via the first control valve; and a second valve hole that opens to other end side in the moving direction of the spool and communicates with the crank chamber, when the pressure of the pressure supply passage between the first control valve and the second control valve is lower than the pressure of the crank chamber, the first valve portion is seated on a first valve seat provided around the first valve hole, and the second valve portion is separated from a second valve seat provided around the second valve hole, and when the pressure of the pressure supply passage between the first control valve and the second control valve is higher than the pressure of the crank chamber, the second valve portion is seated on the second valve seat, and the first valve portion is separated from the first valve seat.
 3. The variable displacement compressor according to claim 2, further comprising: a partition member that partitions the housing chamber into a first space on the first valve hole side and a second space on the second valve hole side and has an insertion hole through which the spool is insertable, wherein a pressure release hole that communicates with the suction chamber opens to the second space, and the spool is disposed so as to be movable with respect to the partition member, and when the second valve portion is separated from the second valve seat, the fluid is discharged from the crank chamber to the suction chamber via the pressure release passage composed by including the second valve hole, a gap between the second valve portion and the second valve seat, the second space and the pressure release hole.
 4. The variable displacement compressor according to claim 3, wherein the spool includes: an internal passage that opens to an end surface of the second valve portion; and a communication hole that causes the internal passage and the first space to communicate with each other, and when the first valve portion is separated from the first valve seat, the fluid is supplied from the discharge chamber to the crank chamber via the pressure supply passage composed by including the first valve hole, a gap between the first valve portion and the first valve seat, the first space, the communication hole, the internal passage and the second valve hole.
 5. The variable displacement compressor according to claim 3, wherein a pressure supply hole that communicates with the crank chamber opens to an inner circumferential wall of the first space, and when the first valve portion is separated from the first valve seat, the fluid is supplied from the discharge chamber to the crank chamber via the pressure supply passage composed by including the first valve hole, a gap between the first valve portion and the first valve seat, the first space and the pressure supply hole.
 6. The variable displacement compressor according to claim 4, wherein the spool includes a sliding contact portion that slides on an inner wall of the housing chamber in the first space, and a second communication hole that causes the pressure supply passage and the first space on the second valve hole side of the sliding contact portion to communicate with each other.
 7. The variable displacement compressor according to claim 3, wherein the spool includes a pressure receiving portion that contacts a first space-side end surface of the partition member in an axial direction when the second valve portion is seated on the second valve seat.
 8. The variable displacement compressor according to claim 7, wherein the spool includes a shaft portion that couples the first valve portion and the second vale portion to each other, and the second valve portion is press-fitted into the shaft portion.
 9. The variable displacement compressor according to claim 3, wherein a second pressure release passage is provided, the second pressure release passage causing the crank chamber and the suction chamber to communicate with each other while bypassing the second control valve, and when the pressure of the pressure supply passage between the first control valve and the second control valve is higher than the pressure of the crank chamber, the second valve portion is seated on the second valve seat, and closes the pressure release passage.
 10. The variable displacement compressor according to claim 3, wherein a notch groove portion that causes the second valve hole and the second space to communicate with each other when the second valve portion is seated on the second valve seat is formed in an end surface of the second valve portion.
 11. The variable displacement compressor according to claim 1, wherein a throttle passage is provided, the throttle passage causing the suction chamber and the pressure supply passage between the first control valve and the second control vale to communicate with each other. 